Photocopier - paper scratches on the OPC

[N_Cook]

ie the normal paper or dust slight scratches , not down to the metal drum
from loose screw or swarf. All quite normal for any OPC. Usually this is ok
but the original toner for this m/c not available, requiring second 1 only
source, supposed compatible, formulation. Very fine scratches seem to hold
the toner , ie exposed bits of latent image retain the toner in the
scratches and so deposit as fine lines on the paper. If too much toner
passed to the OPC then more and more lines appear, so only possible to
produce grey rather than black output. The ac cleaning voltage is now at
maximum of 2.5 KV but some lines are still present with a grey image rather
than black.
Anyone happen to know what needs adding to the toner to make it less sticky
or whatever ? or some other procedure. I'm assuming the narrow scratches are
physically holding the toner but thats only guessing really, decreasing the
transfer voltage of course produces a lighter image and still transfers the
lines, so not an option.
Physically cleaning the OPC or leaving the background heater on all the time
makes no difference. I'm wondering if the toner is too oily and decanting to
a tumbler with blotting paper lining would remove some of the oiliness,
before returning to the hopper. Anyone know of a test for oiliness that
gives some sort of numerical result ?

Incidently anyone know what the marking B stands for, on the preset for
adjusting the 200 to 250V dc voltage of the OPC relative to frame and what
this voltage is called ? The other presets are marked TR for transfer and AC
for the ac cleaning voltage

 

[N_Cook]

ie the normal paper or dust slight scratches , not down to the metal drum
from loose screw or swarf. All quite normal for any OPC. Usually this is ok
but the original toner for this m/c not available, requiring second 1 only
source, supposed compatible, formulation. Very fine scratches seem to hold
the toner , ie exposed bits of latent image retain the toner in the
scratches and so deposit as fine lines on the paper. If too much toner
passed to the OPC then more and more lines appear, so only possible to
produce grey rather than black output. The ac cleaning voltage is now at
maximum of 2.5 KV but some lines are still present with a grey image rather
than black.
Anyone happen to know what needs adding to the toner to make it less sticky
or whatever ? or some other procedure. I'm assuming the narrow scratches are
physically holding the toner but thats only guessing really, decreasing the
transfer voltage of course produces a lighter image and still transfers the
lines, so not an option.
Physically cleaning the OPC or leaving the background heater on all the time
makes no difference. I'm wondering if the toner is too oily and decanting to
a tumbler with blotting paper lining would remove some of the oiliness,
before returning to the hopper. Anyone know of a test for oiliness that
gives some sort of numerical result ?

Incidently anyone know what the marking B stands for, on the preset for
adjusting the 200 to 250V dc voltage of the OPC relative to frame and what
this voltage is called ? The other presets are marked TR for transfer and AC
for the ac cleaning voltage

I should have said the voltage on the centre of the revolving magnet
developer drum , not to the OPC, the retraction voltage ? The votage that
means the toner powder on the OPC that has become discharged from the
exposure light is pulled off, back to the toner supply side, leaving the
latent image.
These fine line toner deposits are adhering more than the 250V "retraction
voltage ?" will pull off but will pull off with the 7.3KV transfer voltage
to the paper.

Anyone know of a source of plain carbon black, fine ground, without silicone
oil/surfactants added , to dilute the supposed proper toner.

 

[N_Cook]

In that are is what looked like an afterthougt 1W resistor to ground,
marked brown black brown. Surely not if a few hundred volts there. With a
good light brought into the area I could then see it is brown black purple.
Just an ordinary looking MO resistor, enamelled ,no glass encapsulation, but
1 Gigohm.

 

[William Sommerwerck]

In that are is what looked like an afterthougt 1W resistor to ground,

marked brown black brown. Surely not if a few hundred volts there. With a
good light brought into the area I could then see it is brown black purple.
Just an ordinary looking MO resistor, enamelled ,no glass encapsulation, but
1 Gigohm.

Wouldn't that be 100M? (10 x 10^7)

 

[Jim Yanik]

Wouldn't that be 100M? (10 x 10^7)

yes.

 

[N_Cook]

yes.

--
Jim Yanik
jyanik
at
kua.net

I'm not used to seing that colour combination.
Measured about 1000Meg, by comparison with a glass cased 1Gohm , with a high
voltage source, it is grey not purple on the third band on rechecking.

 

[Jim Yanik]

I'm not used to seing that colour combination.
Measured about 1000Meg, by comparison with a glass cased 1Gohm , with
a high voltage source, it is grey not purple on the third band on
rechecking.

I'm surprised it would stay 1G for any length of time,with an enamel
coating.

maybe you could post a pic of it.I wonder who makes them?

 

[N_Cook]

I'm surprised it would stay 1G for any length of time,with an enamel
coating.

maybe you could post a pic of it.I wonder who makes them?

--
Jim Yanik
jyanik
at
kua.net

Its just a light blue bodied resistor that looks like any other except for
an unusual colour code. It must be there to discharge any accumulated charge
inside the developer chamber. A resistor with a crimp eye terminal at either
end, looking a bit afterthoughtish. Whether it is 500M or 2000Meg probably
does not matter. I imagine it could be difficult to make a high resistivity
spiral of metal oxide, from my own attempts at making resistive compound for
1 meg pot tracks, very patchy resistivity

As for main thread I got into the generator circuit and temporarily upped
the retract ? voltage up to 350V , for a test. Black lines still there and I
think the image intensty was reduced as well, ie wanted charged, latent
image bits, partially retracted back to the developer, so no solution there.

Apparently, from an industrial chemist, it is possible to get fine ground
pure carbon black from chemical supply companies for some sort of filters ,
not activated charcoal. All laser and copier toner these days have silicone
oil added , perhaps to avoid the use of silicone oil bath/wicks at the
output fuser stage. Enough oil carries through to the output to keep the
paper from sticking to the supposed non-stick finish of the fuser roller or
its pressure roller.

 

[Bob Larter]

ie the normal paper or dust slight scratches , not down to the metal drum
from loose screw or swarf. All quite normal for any OPC.

It's perfectly normal for the OPC to have mild scratches on it. As long
as it's not down to the metal. (Which will give you white lines along
the print.)

Usually this is ok
but the original toner for this m/c not available, requiring second 1 only
source, supposed compatible, formulation. Very fine scratches seem to hold
the toner , ie exposed bits of latent image retain the toner in the
scratches and so deposit as fine lines on the paper.

That's more likely to be due to dirt on the laser window. Give it a wipe
& a blow. A stray hair stuck in there, or in the laser window of the
cartridge will give you a line down the page.

If too much toner
passed to the OPC then more and more lines appear, so only possible to
produce grey rather than black output. The ac cleaning voltage is now at
maximum of 2.5 KV but some lines are still present with a grey image rather
than black.
Anyone happen to know what needs adding to the toner to make it less sticky
or whatever ? or some other procedure. I'm assuming the narrow scratches are
physically holding the toner but thats only guessing really, decreasing the
transfer voltage of course produces a lighter image and still transfers the
lines, so not an option.

There's nothing 'sticky' about the toner. It adheres to the drum from
electrostatic attraction only. If it's sticking to the drum when it
shouldn't be, there's something wrong with the HV, or the IR laser or
cleaning light is not wiping the charge from the drum as it should.

Physically cleaning the OPC or leaving the background heater on all the time
makes no difference. I'm wondering if the toner is too oily and decanting to
a tumbler with blotting paper lining would remove some of the oiliness,
before returning to the hopper. Anyone know of a test for oiliness that
gives some sort of numerical result ?

Dry toner is *never* 'oily'. It's micron-sized particles.

Incidently anyone know what the marking B stands for, on the preset for
adjusting the 200 to 250V dc voltage of the OPC relative to frame and what
this voltage is called ? The other presets are marked TR for transfer and AC
for the ac cleaning voltage

'B' = Bias.

 

[Bob Larter]

Its just a light blue bodied resistor that looks like any other except for
an unusual colour code. It must be there to discharge any accumulated charge
inside the developer chamber. A resistor with a crimp eye terminal at either
end, looking a bit afterthoughtish. Whether it is 500M or 2000Meg probably
does not matter. I imagine it could be difficult to make a high resistivity
spiral of metal oxide, from my own attempts at making resistive compound for
1 meg pot tracks, very patchy resistivity

As for main thread I got into the generator circuit and temporarily upped
the retract ? voltage up to 350V , for a test. Black lines still there and I
think the image intensty was reduced as well, ie wanted charged, latent
image bits, partially retracted back to the developer, so no solution there.

Apparently, from an industrial chemist, it is possible to get fine ground
pure carbon black from chemical supply companies for some sort of filters ,
not activated charcoal. All laser and copier toner these days have silicone
oil added , perhaps to avoid the use of silicone oil bath/wicks at the
output fuser stage. Enough oil carries through to the output to keep the
paper from sticking to the supposed non-stick finish of the fuser roller or
its pressure roller.

*NO!* That is NOT correct! Laser/copier toner is totally dry. The
silicon oil is applied to the fuser roller by a wiper pad, & serves to
prevent the 'cooked' toner on the paper from sticking to the fuser
roller as it exits the fuser assembly.

 

[N_Cook]

It's perfectly normal for the OPC to have mild scratches on it. As long
as it's not down to the metal. (Which will give you white lines along
the print.)


That's more likely to be due to dirt on the laser window. Give it a wipe
& a blow. A stray hair stuck in there, or in the laser window of the
cartridge will give you a line down the page.


There's nothing 'sticky' about the toner. It adheres to the drum from
electrostatic attraction only. If it's sticking to the drum when it
shouldn't be, there's something wrong with the HV, or the IR laser or
cleaning light is not wiping the charge from the drum as it should.


Dry toner is *never* 'oily'. It's micron-sized particles.


'B' = Bias.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

This is a conventional copier, not scanner/laser.
Silicone oil wick/baths at the output have not been used on photocopiers
since the days of sliding top ones, relying on silicones added (sub 1
percent) to the toner instead, not enough to appear oily to the touch but
enough to make sure paper does not stick to fuser drum or silicone rubber
pressure roller. The first one I came across to fix, was wet process toner
in paraffin carrier, 1970s vintage, paper on a roll and a vicious
guillotine.

The toner these days is mainly carbon/charcoal black but also such as
styrene ,styrene acrylic copolymer, polypropylene,metal complex dyes,
methylmethacrylate,styrene butylarylate, silicones and oleic acid

 

[Jim Yanik]

Its just a light blue bodied resistor that looks like any other except
for an unusual colour code. It must be there to discharge any
accumulated charge inside the developer chamber. A resistor with a
crimp eye terminal at either end, looking a bit afterthoughtish.
Whether it is 500M or 2000Meg probably does not matter. I imagine it
could be difficult to make a high resistivity spiral of metal oxide,
from my own attempts at making resistive compound for 1 meg pot
tracks, very patchy resistivity

As for main thread I got into the generator circuit and temporarily
upped the retract ? voltage up to 350V , for a test. Black lines still
there and I think the image intensty was reduced as well, ie wanted
charged, latent image bits, partially retracted back to the developer,
so no solution there.

Apparently, from an industrial chemist, it is possible to get fine
ground pure carbon black from chemical supply companies for some sort
of filters , not activated charcoal. All laser and copier toner these
days have silicone oil added , perhaps to avoid the use of silicone
oil bath/wicks at the output fuser stage. Enough oil carries through
to the output to keep the paper from sticking to the supposed
non-stick finish of the fuser roller or its pressure roller.

toner is a wax compound.waxes are also lubricants.

 

[David Nebenzahl]

toner is a wax compound.waxes are also lubricants.

That's not my understanding: from what I've read, toner is basically a
mixture of pigment (carbon black or equivalent) and plastic (styrene)
that melts onto the printed substrate (paper).

Maybe you're thinking of phase-change/sublimation printing (e.g.,
Xerox/Tektronix Phaser), which does use wax as the carrier.

 

[N_Cook]

That's not my understanding: from what I've read, toner is basically a
mixture of pigment (carbon black or equivalent) and plastic (styrene)
that melts onto the printed substrate (paper).

Maybe you're thinking of phase-change/sublimation printing (e.g.,
Xerox/Tektronix Phaser), which does use wax as the carrier.

I would agree with that summary but add that there are surfactants added to
assist in even distribution of the toner over the OPC, otherwise the coarse
distribution of the iron filings transfer process would be rather patchy.

 

[Jim Yanik]

Heh.I worked for TEK for 21.5 years.
their thermal wax process is a sort of wax-jet deposition thru a printhead.
I've had pretty good looks at TEK's printer mechanics.

just feel the toner that's fused onto the paper;it feels waxy.
Googling showed several references to wax for copier toner.

I would agree with that summary but add that there are surfactants
added to assist in even distribution of the toner over the OPC,
otherwise the coarse distribution of the iron filings transfer process
would be rather patchy.

Isn't it done by electrostatics?

 

[Bob Larter]

That's not my understanding: from what I've read, toner is basically a
mixture of pigment (carbon black or equivalent) and plastic (styrene)
that melts onto the printed substrate (paper).
Correct.

Maybe you're thinking of phase-change/sublimation printing (e.g.,
Xerox/Tektronix Phaser), which does use wax as the carrier.

That'd be my guess too.

 

[N_Cook]

Heh.I worked for TEK for 21.5 years.
their thermal wax process is a sort of wax-jet deposition thru a printhead.
I've had pretty good looks at TEK's printer mechanics.

just feel the toner that's fused onto the paper;it feels waxy.
Googling showed several references to wax for copier toner.


Isn't it done by electrostatics?

--
Jim Yanik
jyanik
at
kua.net

The rotating magnets + iron filings bring the toner close to the OPC and
then the electrostatic voltage on the OPC, set up by the corona wire, pulls
the toner across the gap. Then there should be an even charge distribution,
but although very fine ground, it is finite size and the surfactants can
help to allow easier flow.
This maybe the key to the problem . What is the charge distribution over a
semiconductor surface that instead of being perfectly smooth, has very fine
scratches around it ? Maybe it is possible to reduce the corona voltage.
Previously mistyped as 7.3KV, actually 8.3KV, I've not looked into that
area, separate HV board somewhere, just measured the voltage at the corona
housing .

 

[N_Cook]

I found the neat little Murata corona generator, marked 4.55KV, 0.3mA . I
don't know what the o/p voltage should be
Corona measured as 8.7KV so something not right there, plenty of room to
drop the corona voltage. Not got to the point of monitoring the lines to it
yet nor tried the preset yet, lines to it are 2 grounds, supply, control,
and one marked REM , any ideas what that one means ?

 

[Bob Larter]

The rotating magnets + iron filings bring the toner close to the OPC

Modern laser printers & copiers use monocomponent toner, which has the
magnetic material in each toner particle. You're thinking of older
systems, which used a separate magnetic 'developer' powder to carry the
toner to the drum.

 

[David Nebenzahl]

Modern laser printers & copiers use monocomponent toner, which has the
magnetic material in each toner particle. You're thinking of older
systems, which used a separate magnetic 'developer' powder to carry the
toner to the drum.

Reminds me of the old Kodak* copier I had when I owned a print shop; the
previous owner had bought it for something ridiculous like less than
$1000. The thing was a behemoth, and required lots of maintenance, but
when it was running it would whip out good copies all day long and not
even breathe hard.

I remember having to replace various parts of the "developer" system in
it. Very old school.


* Actually Kodak/Heidelberg, during their short partnership in imaging
systems.